The U.S. aircraft register, updated daily
Approved modifications · supplemental type certificate · current · amended

ST02230SE

The installation of dual Garmin GTX-33ES Mode-S transponders and single or dual Garmin GTN 650/750 panel mounted navigation and global positioning system (GPS) units, or dual Garmin GTX-335R and/or GTX-345R Mode-S transponders and single or dual Garmin GTN 650/750/625/725 panel mounted navigation and GPS units. Held by Butler National Corporation, which holds 18 approved modifications in all. Last revised July 27, 2021. System: instruments and avionics.

What it applies to

Kind of product
Aircraft
Design holder
Learjet Inc.; Learjet Inc.; Learjet Inc.; Learjet Inc.; Learjet Inc.; Learjet Inc.; Learjet Inc.; Learjet Inc.; Learjet Inc.; Learjet Inc.; Learjet Inc.; Learjet Inc.; Learjet Inc.; Learjet Inc.; Learjet Inc.; Learjet Inc.; Learjet Inc.; Learjet Inc.; Learjet Inc.; Learjet Inc.; Learjet Inc.
Models
24, 24A, 24B-A, 24B, 24C, 24D, 24E, 24F-A, 24F, 25, 25A, 25B, 25C, 25D, 25F, 31, 31A, 35, 35A (C-21A), 36, 36A
Type certificates
A10CE, A10CE, A10CE, A10CE, A10CE, A10CE, A10CE, A10CE, A10CE, A10CE, A10CE, A10CE, A10CE, A10CE, A10CE, A10CE, A10CE, A10CE, A10CE, A10CE, A10CE
On this site
Learjet 24 16 registered
Learjet 25 23 registered
Learjet 31 119 registered
Learjet 35 161 registered
The FAA's record
On the FAA's site

What an approved modification is

A supplemental type certificate is the FAA's approval of a change to a certified design: a new engine or propeller, avionics, an autopilot, floats, a parachute, a larger fuel tank, an ice-protection kit. The company holding it may sell the kit and the paperwork to owners of the listed models; the modification then becomes part of that aircraft's record. The FAA's list says what was approved and for which models, not how many aircraft carry it.

Source: FAA supplemental type certificates (Dynamic Regulatory System). Register counts from the FAA register of October 13, 2026.